Curing strategy

[Acoma]

Re: Curing strategy

Badger, I hope you have the time to cure using the new method. I would say to place the blanket on top in a temporary form during the fires too. My thinking is that, as James has said in his own words, you get to push out the mortar faster and better than the old way. It seems the old way teased the mortar and bricks into quick expansions and contractions during initial heats. This likely caused the numerous cracks to ovens during curing. With the blanket the oven keeps the heat with the oven longer and asist with drawing out moisture longer and better. This is my opinion and will be tested within a couple weeks. I will update everyone on this principle too.

Frances, I knew you would laugh. As for the BOM, you hit it on the head. It is to recognize the builders, and of course that should be what matters most. We all love to be recognized in some way.

[gjbingham]

Re: Curing strategy

Badger,
I noticed it several days ago, but let it go. I'm trying not to step on toes too often - be a little PC once in awhile. Good story to go with the avatar!

I'm interested to see how this new curing strategy works out. It sounds laborious, but then again, so is building an oven.

[RCLake]

Re: Curing strategy

I'm interested to see how this new curing strategy works out. It sounds laborious, but then again, so is building an oven.

I'm enjoying it a lot more than I would be starting a fire getting to a set temp and then letting it die. During the day I've been sticking my head in , checking temps and adding wood. A refreshing break from other items I'm doing. I built a WFO to burn wood and finally it's burning wood.

[Acoma]

Re: Curing strategy

I believe that the new method is a successful route. Using the inside keystone area for temp guidence seems best. I notices 50-100 degree difference between walls and dome, and approx. 150 degree difference to the floors. The floor bricks don't matter since they don't have mortart to bond the bricks together. I finished day 2, and now I prepare for Day 3 tomorrow at 500 degree. Likely I will use my standard range of 50-75 degree below, up to the max requested. Works very good going this route, and allows you to step away from time to (limited) time. And so far, NO CRACKS. Also, I would not recommend using a log holder during the curing process, being that it will allow the wood to heat up too quickly, be extremely difficult to manage and spreading of wood/ coals. I would agree to its usage- post cure.

[james]

Re: Curing strategy

Robert,

I want to say thanks for how well you have documented your oven and processes, and how you have approached the project. Your postings will be incredibly useful for other builders for years to come.

Well done.
James

[dusty]

Re: Curing strategy

Robert,

I want to say thanks for how well you have documented your oven and processes, and how you have approached the project. Your postings will be incredibly useful for other builders for years to come.

Well done.
James

James,
You've got the nack. No wonder this forum is the special place it is.
I'm glad I'm in CA 'cause I'm sure that our paths will someday cross. I spend lots of time in La Selva Beach. Going to look you up someday.

KPIG?

dusty

[Inishta]

Re: Curing strategy

If the Italians don't know about curing ovens by now we're in trouble............

[Xabia Jim]

Re: Curing strategy

But it's the Italians that started this new cure recommencation 3 months ago!

When this is all said and done, and there has been some good experience and recommendations by recent builders, maybe James can post a new curing sticky from what's been learned.

Two questions I have?? Is it bad to let a log smolder in the oven all night or use some other device to maintain the heat level before kicking up to the next temperatures? and,

Should the oven be allowed to cool down to ambient temperatures (how many times?) before you go for a very hot fire?

This masonry ovenwork goes through this high range of temperature from below 0 to over 1000 C, many, many times.
STRESS Almost like the stress put on the new builder doing curing fires!!!!

[david s]

Re: Curing strategy

Potters fire their kilns slowly to avoid stress on both the kiln and the wares. For a biscuit firing (unfired wares) the schedule should not exceed 100 C/hr We go much faster than that. Water continues to be expelled up to 500 C as mechanical water and chemical water.

[david s]

Re: Curing strategy

Potters fire their kilns for a biscuit firing (unfired clay) at 100 C/hr so the kiln and the wares are not too stressed. We go much faster than this with our WFO's so the initial curing should be much slower. Mechanical water is eliminated up to 300C but chemical water is not fully eliminated until around 500 C which explains why you go through so much fuel when curing and why the oven continues to improve in performance after susequent firings. Hope this helps.

[Xabia Jim]

Re: Curing strategy

David, where I'm coming from is thinking about the full range of the heating and cooling cycle as it relates to the thermal expansion and contraction. By cooling to ambient, you get a broader range of expansion during the cure. Since you will do this many times over the life of the oven, I'd think that would be good....but I could be bass ackwards, maybe it's better to do that after you've driven out the moisture.

From my days making ceramics and pottery I remember that bisqueware is usually dry. As I recall wet bisquit will surely crack. Neat analogy to WFO's

[Acoma]

Re: Curing strategy

Well, I have lots of cracks along outside perimeter, marathon types. Long distance, perimeter distances, and all shooting to the top. 4-5 of them. I have a 1/4 to 1/2 inch mortar as shell, not helping, but the cracks don't run to the inside, just to the mortar within bricks on outside of dome. I cannot see any cracks on the inside though. I cannot verify this part because the inside is as black as a coal miners face. I am proceeding with the curing strategy, and I will use furnace cement with some grinding once the curing process is complete.

[Inishta]

Re: Curing strategy

But it's the Italians that started this new cure recommencation 3 months ago!

Precisely.............I read James first post on this thread as the Italians putting FB users right on curing ovens...........something that I was never informed about when we built our oven. Thank goodness I found FB forum.

[david s]

Re: Curing strategy

My point about the biscuitware analogy was that although it may appear dry there is still water in it and that takes energy to remove it, which is still being eliminated well over waters boiling point of 100 C . Why would you want to deliberately make the material expand and contract at this delicate stage? It doesn't make sense. Just a gradual expansion is a better way. Castable refractory firing schedules suggest a very slow and steady increase. Theyre the manufacturers so they should know their product.

[Acoma]

Re: Curing strategy

David, I don't believe you are being questioned. I believe we are evolving with techniques best fit to drive out the moisture, eliminate or minimize cracks, and strenghten the oven with best practice. The old philosophy for ovens was updated recently upon world practices. Should this method you speak of be a new and evolving technique to revolutionize the curing process, then that is AWESOME! My idea is for you to apply this practice you speak of to an oven you plan to build, even a guiny pig mini oven, does not matter. If it works with no cracks, then wala...